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Zcash activates NU7, cutting block target to 25 seconds

Zcash activated NU7 at block 3,543,405, cutting target block spacing from 75 seconds to 25 seconds and shortening waits for private payments.

Crypto Daybook Newsroom2 min read

Zcash activates NU7, cutting block target to 25 seconds

Zcash activated its NU7 network upgrade at block 3,543,405, cutting the target time between blocks from 75 seconds to 25 and potentially making private payments quicker to confirm. CoinDesk reported that the block was mined at 02:34 UTC on Nov. 6.

What changed when NU7 went live?

The upgrade makes Zcash blocks arrive at a faster target rate. A block is a batch of transactions added to the network; its confirmation is one step toward a payment being accepted. The shorter target means a service accepting one confirmation could see a shorter wait.

The network had not yet reached the new pace immediately after activation. CoinDesk reported that 225 blocks were mined by 04:59 UTC, averaging about 39 seconds apart, while mining difficulty adjusted. So the 25-second figure is the target, not a guarantee that every payment will confirm in exactly that time.

How much faster could private payments be?

Zcash can hide a payment’s sender, recipient and amount. For a private payment, NU7 also limits how much shielded activity can go into each block. These limits are designed to keep the extra work for wallets manageable as blocks arrive more often. Wallets scan the chain to find payments meant for them.

According to the NU7 deployment specification, the changes bound wallet validation and syncing costs while reducing confirmation delays. CoinDesk said the specification estimates that simple private payment capacity could rise from about three per second to more than six. Actual wait times still depend on how many confirmations a merchant, exchange or other service requires.

What else does the upgrade change?

NU7 sends 60% of transaction fees to a public reserve for future block rewards; miners receive the other 40%. The reserve is scheduled to begin feeding rewards around February 2031. The specification says this mechanism does not raise Zcash’s 21 million ZEC supply cap.

The upgrade also makes version 4 transactions invalid. Since Zcash’s original Sprout privacy pool uses that transaction format, any funds left there became unspendable when NU7 activated. CoinDesk reported that about 12,224 ZEC remained in Sprout at the time, and that no recovery plan had been approved.

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